CN105157616B - A kind of shadow moire profilometry device, its scaling method and measuring method - Google Patents

Abstract

The present invention provides a kind of shadow moire profilometry device, its scaling method and measuring method, and measurement apparatus includes three line sources of red, green, blue, a colourful CCD video camera, a grating and a precision displacement platform；Three line sources of red, green, blue and colourful CCD video camera collinearly be arranged at grating side and parallel with grating face；Described grating is arranged on precision displacement platform；Described three line sources of red, green, blue are arranged in colourful CCD video camera side.Invention also provides the scaling method of above-mentioned shadow moire profilometry device and measuring method.The problem of longer testee time and not high precision being measured instant invention overcomes existing phase shift shadow Moire measurement apparatus and measuring method.

Description

A shadow moiré profile measurement device, its calibration method and measurement method

technical field

The invention relates to the technical field of optical precision measurement, in particular to a shadow moiré profile measurement device, a calibration method and a measurement method thereof.

Background technique

Shadow Moiré profilometry has high precision and has become the preferred technique for measuring the deformation of objects under heat or force. Moreover, the JEDEC high temperature measurement industry standard also recommends the shadow Moire method as one of the main techniques for this type of measurement. So far, a large number of documents have reported the application of shadow moiré technology in the IC industry, and related documents are still emerging. These applications include chip package surface profile measurement, silicon wafer flatness measurement, and topography measurement of silicon wafer integrated circuits. However, with the continuous reduction of electronic packages and the diversification of designs, the new manufacturing process puts forward the measurement requirements of online or in-situ, high precision and full inspection for measurement technology. This feature also requires the existing measurement technology to adapt to the changes in the characteristics of the product under test and make corresponding improvements so that the measurement device has optimal parameters to obtain high-contrast Moiré fringe patterns, and combined with phase shift technology, it will be reliable without omission Automatically extract measurement information, etc. However, limited by the manufacturing level of components and measurement algorithms, traditional shadow moiré measurement devices often use black-and-white CCD cameras, and change the phase of the measurement field of view by moving the grating. The phase shift process requires mechanical movement, and the process is time-consuming and laborious. In addition, although some devices try to introduce phase shift into the measurement field of view by time-sharingly controlling the on and off of different light sources, this method cannot complete the acquisition of the fringe pattern at the same time, and the requirements for the positioning of the light source are too strict to achieve accurate positioning of the light source. Measurement results are susceptible to variations in the light field and cannot be reliably measured. Another disadvantage of the traditional shadow moiré device is that it needs to make a calibration block during the calibration process. During the calibration, it is necessary to calculate the device parameters based on the known height information of the calibration block, or to record the change law of the light intensity at a certain point in the measurement field of view. The implementation of the method is complicated, and the calibration cannot be completed quickly.

Contents of the invention

The object of the present invention is to provide a shadow moiré profile measurement device, its calibration method and measurement method, so as to overcome the problems that the existing phase shift shadow moiré measurement device and measurement method take a long time to measure the measured object and have low precision .

Technical scheme of the present invention is:

A shadow moiré profile measuring device, the measuring device includes three line light sources of red, green and blue, a color CCD camera, a grating and a precision displacement platform; the three line light sources of red, green and blue The one collinear with the color CCD camera is arranged on one side of the grating and parallel to the grating surface; the grating is arranged on the precision displacement platform; the three line light sources of red, green and blue are arranged on the side of the color CCD camera.

The precision displacement platform is a manual precision displacement platform or an electric precision displacement platform.

The red, green and blue line light sources are arranged at equal intervals on one side of the color CCD camera.

A calibration method for a shadow moiré profile measuring device, comprising the following steps:

Step 1: Place the measured object under the grating, turn on any one of the three line light sources of red, green, and blue monochromatic light sources, move the grating several times at equal distances through the precision displacement platform, and take and record the phase shift fringe pattern;

Step two, using a phase shift extraction algorithm to determine the phase shift due to the moving grating.

A measuring method of a shadow moiré profile measuring device, comprising the following steps in sequence:

Step 1: Adjust the grating to the initial position, place the measured object under the grating, and turn on the red, green, and blue line light sources at the same time to generate complex-color moiré fringes on the surface of the measured object, and then the color CCD camera takes a single shot Conditional uptake of complex moiré fringes;

Step 2, separating the ingested complex-colored moiré fringes to form monochromatic moiré fringes to obtain a phase-shifted moiré fringe pattern for demodulating the surface topography of the measured object;

Step 3, normalize the data obtained in step 2, and then use the principal quantity analysis method to extract the measurement phase;

Step 4, using the unwrapping method to perform phase unwrapping on the measurement phase extracted in step 3;

Step five, according to the measurement sensitivity and the unfolded phase, perform phase height mapping to complete the measurement.

Beneficial effects of the present invention:

1. The structure of the measurement device of the present invention is simple: the structure of the measurement device proposed in the present invention adopts a color CCD camera, which can simultaneously complete the collection of phase shift fringe patterns, and can simultaneously complete the fringe patterns by using R, G, and B light sources to irradiate the measurement grating phase shift; compared with the traditional shadow moiré method, the present invention improves the measurement structure, reduces the influence of the diffraction of light and the reflected light on the surface of the grating on the fringe contrast and the sinusoidal distribution of light intensity; its installation requirements are low, and the measurement system is not increased the complexity of

2. The method for measuring the topography of the surface of the object to be measured is simple: the object to be measured is placed under the grating, and the measurement can be automatically completed at one time, and the measurement speed is increased to meet the measurement requirements of online or in-position and full inspection; The misaligned phase-shift shadow moiré demodulation technology makes the measurement accuracy reach sub-micron level in a large dynamic range; the method can be used to measure the surface topography of the object, and the surface topography of the measured object can be automatically measured. The shape quickly lays the groundwork.

3. The present invention also provides a set of fast calibration methods for the device: this method does not use calibration blocks, and only relies on the shadow moiré device itself to realize fast and convenient calibration of measurement sensitivity and structural parameters. The present invention can be directly used in the measurement process The measurement sensitivity is calibrated in the process, which improves the measurement efficiency;

4. The application requirements of the present invention are low: the present invention does not require the consistency of the light source, has low requirements on the environment, and is suitable for the measurement needs of industrial occasions.

Description of drawings

Fig. 1 is a schematic diagram of a measuring device of the present invention;

Fig. 2 is the schematic diagram that measuring method of the present invention implements;

In the figure, 1-red, green and blue three line light sources, 2-color CCD camera, 3-grating, 4-object under test.

detailed description

Below in conjunction with accompanying drawing, the present invention is further described, a kind of shadow moiré profile measuring device as shown in Figure 1, described measuring device comprises red, green, blue three line light sources 1, a color CCD camera 2, a grating 3 and a precision displacement platform; the red, green and blue three line light sources 1 and the color CCD camera 2 are collinearly arranged on one side of the grating 3 and parallel to the grating surface; the grating 3 is arranged on a precision displacement platform The platform is flat and the precision displacement platform is a manual precision displacement platform or an electric precision displacement platform. The precision displacement platform can drive the grating 3 to move along the direction vertical to the grating surface; the three line light sources 1 of red, green and blue are equally spaced or approximately equal The intervals are arranged on one side of the color CCD camera 2 .

The following describes the calibration method based on the above device:

Referring to Fig. 2, the optical axis of the color CCD camera 2 is perpendicular to the grating surface, and the red, green, and blue line light sources 1 are arranged at equal intervals. The optical center of the color CCD camera 2 and the center of the light source are placed at a distance h from the grating plane. The distance between a line light source and the optical center of the color CCD camera is d.

Before actually measuring the surface topography of the object, the measurement device is first calibrated. This calibration operation is only required for the first measurement. The specific steps of the calibration method are:

Step 1. Place the measured object 4 under the grating 3, turn on any one of the red, green, and blue line light sources 1, and move a quarter of the grating 3 through a manual precision translation stage or an electric precision translation stage The distance between fringes is 3 times, and the phase shift fringe pattern is photographed and recorded;

Step 2. Use the phase shift extraction algorithm to determine the phase shift δ due to the moving grating 3. According to the determined phase shift δ, the measurement sensitivity S is: In the formula, Δh is the distance that the precision displacement platform moves each time.

After completing the calibration work of the measuring device, the surface topography of the measured object 4 is measured, and the specific steps of the measuring method are:

Step 1, place the measured object 4 under the grating 3, turn on the red, green, and blue line light sources 1 at the same time, and generate complex-color moiré fringes on the surface of the measured object 4, and there is a certain phase shift between the moiré fringes of each color amount, and then the color CCD camera 2 captures the complex color moiré fringes under the condition of a single shot;

Step 2, separating the ingested polychromatic moiré fringes in the computer to form monochromatic moiré fringes, and then obtaining a phase-shifted moiré fringe pattern for demodulating the surface topography of the measured object 4;

Assuming that A _k (x, y) is the background, B _k (x, y) is the modulation item, φ _k (x, y) is the phase, and k=1, 2, 3 is the serial number of the time domain fringe, then the captured fringe pattern The light intensity can be expressed as:

I _k (x, y) = A _k (x, y) + B _k (x, y) cos[φ _k (x, y)];

Step 3, normalize the data obtained in step 2, remove the fringe background and amplitude, and eliminate the influence of color crosstalk on the measurement; then use the principal quantity analysis method to extract the measurement phase;

The regularization process described is:

where n is the number of pixels;

Step 4, using the unwrapping method to perform phase unwrapping on the measurement phase extracted in step 3;

Step five, according to the measurement sensitivity S and the unfolded phase, perform phase height mapping to complete the measurement;

To continue the measurement, repeat the surface topography measurement step.

Through the above measurement method, it can fully combine the advantages of non-contact full-field measurement of shadow moiré three-dimensional profilometry and high precision of phase measurement technology, and surpass the limitations of traditional shadow moiré technology system in the measurement process; Therefore, this patent proposes a new three-dimensional sensing technology based on red, green, blue (RGB) light sources for phase-shift shadow moiré. The color CCD provides guarantee for fast sampling of data in a single shot. By arranging the position of the light source, the polychromatic moiré and fringe measurement phase modulation is realized, and then the light field is corrected to normalize the fringe image data, and the high-precision phase shift algorithm and variable precision phase unwrapping are developed. The method and system calibration technique map the absolute phase to the measurement height space from coarse to fine.

The content of the present invention is not limited to the examples listed, and any equivalent transformation of the technical solution of the present invention adopted by those of ordinary skill in the art by reading the description of the present invention is covered by the claims of the present invention.

Claims (3)

1. a kind of measuring method of shadow moire profilometry device, it is characterised in that：

The measurement apparatus that this method is used includes three line sources of red, green, blue（1）, a colored CCD video camera（2）, one Individual grating（3）With a precision displacement platform；Described three line sources of red, green, blue（1）With colored CCD video camera（2） Conllinear is arranged at grating（3）Side and parallel with grating face；Described grating（3）It is arranged on precision displacement platform；It is described Three line sources of red, green, blue（1）It is arranged in colored CCD video camera（2）Side；

Described measuring method comprises the following steps successively：

Step one, by grating（3）Adjust to initial position, testee（4）It is placed in grating（3）Lower section, at the same open it is red, green, Blue three line sources（1）, secondary color Moire fringe is produced on testee surface, then colored CCD video camera（2）Clapped in single Secondary color Moire fringe is absorbed under the conditions of taking the photograph；

Step 2, separates the secondary color Moire fringe of intake to form monochromatic Moire fringe, obtains being used to demodulate testee（4）Table The phase shift moire fringe figure of face pattern；

Step 3, by the data Regularization obtained by step 2, then extracts measurement phase with main amount analytic approach；

Step 4, the measurement phase extracted with de-packaging method to step 3 carries out phase unwrapping；

Step 5, according to measurement sensitivity and the phase of expansion, carries out Phase-height mapping, completes measurement.

2. the measuring method of shadow moire profilometry device according to claim 1, it is characterised in that：Described precision Displacement platform is manual precision displacement table or electric precision displacement platform.

3. the measuring method of shadow moire profilometry device according to claim 1, it is characterised in that：It is described it is red,

Green, blue three line sources（1）It is equidistantly spaced from colored CCD video camera（2）Side.